Since having my 2003 TD6 gearbox repaired I now get trans a Trans failsafe alarm when traveling on gravel roads. The alarm come up on the display I stop turn off ignition for a few minutes and can then drive for 100+ Kms then the alarm may reapear. Checking the alarms with a faultmate brings up 4 unknown codes. I have checked the gearbox multicable plug cleaned the connections with switch cleaner checked the cable but the alarm still apears although no other symptoms show. Has anybody any suggestions, I have checked all the earth connections I can find. Any ideas would be appreciated.

Unknown codes?

Any numbers?

May need T4 diagnostic to reveal? Best to get it identified first.

Problem could be anywhere as all the ECU's talk to each other to confirm everything is OK.

I would work my way back from the wheels : ABS / Height Sensors / Steering Sensors / Wiring / ECUs

You may also need to check the wiring between the Transfer box ECU (behind battery) and the transfer box. A Resistance check should do it. .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Since cleaning the multipin plug at the rear of the gearboxthe fault is now much more intermitant and only brings up one alarm at a time code 6022 or 6023 do these mean anything to any one. Regarding taking it to a dealer we live 300 kms from the nearest LR dealer and don,t trust them anyway. Profit first service last. Nearest ind in Cape Town 660kms away